The Alborán Sea, the stretch of water fronting Marbella, is the only place in the Mediterranean where Atlantic and Mediterranean currents meet head-on — a collision that makes it the most biologically productive basin in the whole sea. That single hydrographic quirk explains the dolphins. Nutrient-rich Atlantic water pours through the Strait of Gibraltar and fans east along the Costa del Sol, feeding sardine and anchovy shoals, which in turn hold resident pods of common and bottlenose dolphins within a few nautical miles of the shoreline. Marbella's relationship with that water is older than its marinas. The Phoenicians worked the coast for salted fish; the Romans built garum vats along the Málaga littoral; Moorish Marbella traded from a modest beach anchorage until the Christian conquest of 1485. The modern harbour came much later. José Banús opened Puerto Banús in May 1970, and the Andalusian fishing coast acquired, almost overnight, a berth for 915 vessels beneath the 1,215-metre limestone ridge of La Concha. What began as a yacht address is now the departure point for nearly every marbella dolphin cruise operating on this coast. What matters today is the science underneath the sightseeing. The Alborán basin supports striped, common and bottlenose dolphins year-round, alongside seasonal pilot whales and the occasional loggerhead turtle. Since 2006 the western Mediterranean has held Cetacean Sanctuary status under the ACCOBAMS agreement, and Spanish law sets a 60-metre minimum approach distance, a five-knot ceiling within 300 metres of a pod, and a hard ban on swimming with wild cetaceans. Responsible marbella dolphin cruise tours are built around those limits rather than against them, cutting engines and letting curious animals close the gap themselves. The vessels reflect the port they leave from. Sailing catamarans dominate — broad, shallow-draught, quiet under canvas, and stable enough that spotting from the trampolines requires no sea legs. Sunseekers, built in Poole but synonymous with Banús since the 1980s, offer the harbour's other register entirely. Both trace the same arc: west past Guadalmina toward Estepona, or east along the Golden Mile with Marbella's whitewashed old town and the Sierra Blanca behind it. The port itself is free to enter, open 00:00–23:59 every day of the week, and sits at Puerto Banús, 29660 Marbella, Málaga, Spain. Individual operators set their own cruise fees. Between the breakwater and the open Alborán lies roughly twenty minutes of motoring — and, on most days, the first dorsal fin.